Eyepiece system
An eyepiece system includes a single positive lens and a cemented lens assembly having a positive biconvex lens and a negative lens cemented thereto, in this order from the object side. The eyepiece satisfies the relationships defined by d<0.3f, and f.sub.1 >1.5f, wherein "d" represents a distance between the single positive lens and the cemented lens assembly, "f" a focal length of the whole lens system, and "f.sub.1 " a focal length of the single positive lens.
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Claims
1. An eyepiece system comprising:
- a lens group consisting of a single positive lens;
- a cemented lens assembly having a positive biconvex lens and a negative lens cemented thereto, said lens group and said cemented lens assembly being arranged in this order from an object side; and
- said eyepiece system satisfying the following relationships:
- said single positive lens is provided with at least one aspherical surface which satisfies the following relationship:
- "d" represents a distance between said single positive lens and said cemented lens assembly;
- "f" represents a focal length of the whole lens system;
- "f.sub.1 " represents a focal length of said single positive lens;
- "r" represents a radius of paraxial curvature of said aspherical surface; and
- "r.sub.h " represents a radius of curvature of said aspherical surface in a meridional section at an optional height from the optical axis, said optional height not being equal to zero.
2. The eyepiece system according to claim 1, wherein the eyepiece system satisfies the following relationship:
- ".nu..sub.+ " represents an Abbe number of said positive lens of said cemented lens assembly; and
- ".nu..sub.- " represents an Abbe number of said negative lens of said cemented lens assembly.
3. An eyepiece system consisting of three lenses consisting of a single plastic lens which is provided with at least one aspherical surface and two glass lenses cemented to each other, said single plastic lens being located closer to an object to be viewed than the cemented glass lenses.
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Type: Grant
Filed: Jan 11, 1996
Date of Patent: Aug 4, 1998
Assignee: Asahi Kogaku Kogyo Kabushiki Kaisha (Tokyo)
Inventor: Moriyasu Kanai (Tokyo)
Primary Examiner: Georgia Y. Epps
Assistant Examiner: Evelyn A. Lester
Law Firm: Grennblum & Bernstein P.L.C.
Application Number: 8/585,161
International Classification: G02B 2500;
